A031884 Smaller of a pair of consecutive lucky numbers with a gap of 2n.

1, 3, 15, 79, 141, 51, 787, 495, 171, 937, 903, 745, 2851, 1611, 1057, 3811, 5769, 4893, 8719, 10683, 9841, 24073, 9567, 28245, 25687, 3507, 26943, 35743, 44805, 51979, 64723, 23205, 50779, 51475, 264075, 155833, 238057, 178755, 143311, 400591, 223095, 181581, 466813

Offset: 1

Author

Patrick De Geest

Keywords

• nonn

Comments

a(n) is the first occurrence of a difference of 2n between A000959(k+1) and A000959(k). - Robert G. Wilson v, May 12 2006

a(136) > 10^9. - Donovan Johnson, Dec 07 2011

Unknown terms a(166), a(176), a(178), a(182), and a(185) through a(209) are all greater than 10^10. - Kevin P. Thompson, Nov 24 2021

Examples

			a(4) = 79 since the lucky numbers A000959(20) = 79 and A000959(21) = 87 are the first consecutive pair with difference 2*4 = 8.
		

Links

• Kevin P. Thompson, Table of n, a(n) for n = 1..165 (terms 1..135 from Donovan Johnson)
• Kevin P. Thompson, Table of n, a(n) for n = 1..210 with unknown terms

Crossrefs

Cf. A000959, A031885, A031883, A031158, A031886, A031888, A031890, A031892, A031894, A031896, A031898, A031900, A031902.

Programs

Mathematica

lst = Range[1, 10^6, 2]; i = 2; While[ i <= (len = Length@lst) && (k = lst[[i]]) <= len, lst = Drop[lst, {k, len, k}]; i++ ]; f[n_] := Block[{k = 1}, While[t[[k + 1]] - t[[k]] != 2n, k++ ]; t[[k]]]; Array[f, 41] (* Robert G. Wilson v, May 12 2006 *)

Extensions

More terms from Robert G. Wilson v, May 12 2006